Since 1.4.1572.x you can review the sharing status of page layers.

On the View menu, select Shared Layers Info.

If the page contains no shared layers, the warning "No layer of this page is shared!".

Otherwise, for every shared layer it is displayed the name of the layer, and the full name of all editions and pages where the layer is shared. For layers that are not shared, a "Not shared" info is displayed.